Worldwide, many oil fields have reached a near depleted state where the standard extraction methods no longer provide profitable results. A typical oil field goes through several phases, Phase I or primary recovery, Phase II or secondary recovery, and Phase III or enhanced oil recovery (EOR). Primary recovery extracts about 30% of the oil from the reservoir and is achieved by relying upon the existing underground gas pressure. Secondary recovery typically extracts an additional 10% to 30% of the underground oil using water recovery or other similar methods. EOR uses CO2 gas flooding to extract additional oil from the reservoir, extending the productive life of the field by 10 to 25 years. Towards the end of Phase II, an oil field's productivity enters a low profitability plateau and is considered depleted. At this point, the field is either capped and abandoned or minimally operated unless EOR techniques can be profitably applied.
Domestic oil provides over 7 million barrels per day of petroleum production. As domestic oil production declines, thousands of depleted oil and natural gas wells remain in the United States. These depleted wells collectively possess significant amounts of petroleum resources that cannot currently be extracted using conventional extraction techniques.
EOR in many instances is not an economical technique for most oil fields due to costs and difficulty associated with transporting CO2 to the site of use or building a power plant at the site of the depleted well.
Accordingly, as recognized by the present inventors, what is needed is a method and apparatus for extracting oil/petroleum from the ground or from oil wells, such as depleted oil wells.
It is against this background that various embodiments of the present invention were developed.